Arrangement for transmitting wireless signals



April 1933- M. J. 0. STRUTT El AL 0 ARRANGEMENT FOR TRANSMITTING WIRELESS SIGNALS Filed Sept. 5, 1929 j y'i INVENTOR MAXIMILIMN .muus om STRUTT 'AND BY POPKO RE! a: p|JK51fERHu|$.

ATTORNEY Patented Apr. 18, 1933,

UNITED STATES PATENT OFFICE MAXIMILIAAN JULIUS OTTO STRUTT AND POPKO REINDER DIJ'KSTERHUIS, 0F EINDHOVEN, NETHERLANDS, ASSIGNORS TO RADIO CORPORATION OF AMERICA, A

CORPORATION OF DELAWARE ARRANGEMENT FOR TRANSMITTING WIRELESS SIGNALS Application filed September 5, 1929, Serial No. 390,526, and in the Netherlands September 1, 1928.

This invention relates to antennae or aerials adapted to transmit wireless signals and more particularly to those having a directional efiect.

This invention has for its object a process and an arrangement for varying at will the direction in which the signals are transmitted.

Aerial systems have been already proposed, in which'the radiation in particular directions can be amplified or attenuated by using at least three aerials which, dependent upon the direction desired, can be energized in variable, mutually different phases. With these systems rather complicated devices for controlling the relative phase are required.

According to this invention, a process for varying thejdirection is carried out, in which a beam of electro-magnetic waves is radiated by a directional aerial system whose feeding is efl'ected in such manner that the amplitude of the oscillations in the variousradiators of the: system regulably increases or decreases from one side to the other, the phases in the said radiators being, however, maintained mutually equal.

For carrying out this process use should preferably be made of an aerial constituted by a transmission line and two or more radiators which together with the said transmission line are located in a plane while the supply of the radia ors can be efi'ected at will with mutual difference of amplitude at one or more points of the transmission line.

Further explanation of the invention follows with reference to the accompanying drawing which represents diagrammatically,

by way of example, embodiments of the inaerial which is fed only on one side.

As appears from Figure 1, an aerial 1 consists of atranslnission line constituted by two horizontal conductors or feeders 2 which are located the one above the other a half Wavelength apart and between whichare arranged at distances of a half-wavelength a plurality of radiators 3 having free electrical ends and each having a length of a half wave-length. On both sid s the transmission line is closed by a conductor 1 which, electrically speaking, is made twice as long as a half wave-length by means of a coil 5, the feeding being effected on both sides at one of these halt wave-lengths by means of transformers 6. These tran formers are supplied by leads 7 from an autotransformer 8, which is coupled to the transmitter by means of leads 9. Variable inductances 10 are inserted in the two feeders in order to equalize the phase of the currents passings through the said feeders.

it is also possible to make the conductors 4 spatially twice a half-wave length long, which is constructively still more advantageous. This is represented in Figure 2'.

As the ends of each of the conductors 4- are in the same phase and the radiators 3 are connected at distances of half a wave-length alternately to the upper and the lower conductor 2, it may be obtained that all the radiators are energized in the same phase, so that a directional radiation is produced whose main direction under normal conditions is perpendicular to the plane of the aerial.

It is possible to vary this main direction of radiation in a simple manner between the definite limits by rela ively varying the amplitude of the currents supplied on both sides to the aerial. This variation of amplitude can be effected by the displacement of variable tapping points 11 on the auto-trans former, the phase-coincidence of the currents supplied along the two feeders 7 being controlled with the aid of the above mentioned adjustable inductances 10.

Figure 3 represents an aerial system which is fed only on one side. In this case the desired variation of amplitude in the successive radiators is obtained owing to the fact that in each of the conductors 2 between the successive points of connection of each two radiators are connected in series, a variable resistance 12 and a variable inductance 13, the latter being destined for the phasecorrection.

. With this armngement, however, the directive efl'ect can onl be influenced at the cost of extra energyowes in the transmission line; such losses are obviated by havin 5 the u efiectgdfi two or ngorepoints themiam.

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